Aerobic decomposition of wastes is well known. Composting, for example, has been practiced in agriculture for centuries. However, most modern landfills are operated in an anerobic manner because of regulatory requirements. Nonetheless, there are advantages to aerobic decomposition of the types of wastes that are found in landfills and, accordingly, considerable investigation and interest exists in this art.
For example, in lysimeter tests conducted by the University of South Florida, it was shown that degradation of municipal solid wastes (MSW) can be enhanced by the application of water, the recycling of leachate, and the addition of air. Employing these processes on shredded MSW in a vertical lysimeter, waste settlement rates of greater than 25% were observed within 60 days. In addition, these tests showed significant improvement in leachate quality based on biochemical oxygen demand (BOD) and volatile solids. In light of this work and other MSW treatment studies, it is estimated that landfills that have at least a 50% organic fraction of waste, could achieve a MSW settlement of a least 15% by volume.
Although there are advantages to aerobic decomposition of wastes and keen interest in this art, methods for the demonstrated safe operation of landfills in an aerobic manner or for the cost-effective conversion of landfills from anaerobic to aerobic operation are not known prior to the present invention.